The actress is one of a number of Hollywood stars who have urged Los Angeles prosecutors to do more to prevent celebrity harassment - in particular the increasingly aggressive tactics of the paparazzi, says the BBC's David Willis in Los Angeles.

Rutter had told the actress he was giving her "first refusal" to buy the photos taken 11 years earlier when she was an unknown teenage model, presenting her with a forged model release form.

If she did not pay up, he said he would offer the photos for sale worldwide.

Ms Diaz told the court the photographer told her the buyers were going to put the pictures in magazine spreads and on buses and advertising boards.

The actress contacted the authorities, who arrested Rutter after a sting operation.

Injunction

Rutter denied in court that he had forged Ms Diaz's signature on the release form. However, he accepted the signature was probably not real.

He was charged with theft over the alleged blackmail scheme, and perjury for testifying that the signature was authentic.

Ms Diaz, 32, said in court she had never signed a release form for the shoot.

A permanent injunction has been issued prohibiting Rutter from distributing the picture.

Rutter was taken into custody after the verdict. He is scheduled to be sentenced on 15 September.

The district lawyer's office is now considering the possibility of bringing conspiracy charges against agencies or individuals who orchestrate photo ambushes.

They are also looking into whether the dogged pursuit of celebrities by the paparazzi constitutes a crime.